An air foil thrust bearing is a bearing that supports a thrust of a rotary body by using an air film and pressure distribution generated between a shaft that rotates at a high speed and an air foil, and is distinguished from a ball bearing or a roller bearing that reduces friction through rolling and a slide bearing that supports a thrust by using an oil film.
The air foil thrust bearing is used in turbo machinery such as a compressor or a blower.
As illustrated in FIG. 1, in the air foil thrust bearing, bump foils 80 are disposed on an upper surface of a base plate 60 and top foils 90 are disposed on the upper surfaces of bump foils 80.
Each top foil 90 may have an inclined section 99 and a flat portion 92, and each bump foil 80 may comprise a plurality of bumps 8.
When operation of a rotor 10 causes a bearing disk 20 to rotate, pressure is formed between top foils 90 and bearing disk 20 to support a load as air is introduced along the inclined sections 99 of top foils 90.
Edge portions 94 of the top foils 90 may be attached to base plate 60, for example by welding, and edge portions 84 of the bump foils 80 also may be attached to the base plate 60, again using a process such as welding.
Thus, in the conventional air foil thrust bearing, top foils 90 are individually disposed on bump foils 80 and the number of top foils 90 must equal the number of bump foils 80. Accordingly, the number of assembled components increases and the assembly process becomes more complex. For example, when six top foils 90 are installed, six corresponding bump foils 80 must be installed and the total number of the components is twelve.
Further, in the conventional air foil thrust bearing, because the edge portions 94 of top foils 90 and the edge portions 84 of bump foils 80 are attached to base plate 60 through welding, the edge portions 94 of the top foils 90 and the edge portions 84 of the bump foils 80 must have sufficient lengths for welding. This increases the dead zones of flat portions 92 of top foils 90, such that the flat portions 92 of the top foils 90 are shortened, and accordingly, the load support area is reduced resulting in decreased stability during high-speed driving due to the low load support force.